Cellulosic material resistant to mustard gas penetration



This invention relates to the treatment of fabrics and clothing forprotection against the action of mustard gas and similar vesicants.

It is known that N-chloroamides, in particular the compounds referred toherein as tertiary N-chloroureas, are of value for protecting fabricsagainst penetration by vesicants of the type of mustard gas(beta,beta'-dichlorodiethylsulfide). However, a serious disadvantage ofthe N-chloroamides is their tenderizing eifect on fabrics, particularlyof the cellulosic type, with the result that the fabric eventuallybecomes weak and unsuitable for use in clothing. Another disadvantage isthat the N-chloroamides, particularly the N-chloroureas, are somewhatunstable and undergo decomposition with loss of chlorine with the resultthat, after varying periods of time on the fabric, they lose theirefficiency. These problems are particularly serious under conditions ofhigh temperature and high humidity such as generally prevail in tropicaland equatorial regions. 1

An object of this invention is the provision of a process for givingfabrics, particularly fabrics permeable to air such as cellulosicmaterials, protection against penetration of vesicant vapors while atthe same time preventing or retarding deterioration of the fabric. Afurther object is the manufacture of new and useful products comprisingcellulosic material which has been treated with an antivesicant agentand a stabilizer against fabric deterioration, and which is permeable toair after said treatment. Other objects will appear hereinafter.

These objects are accomplished, in accordance with the invention, bytreating a fabric with an N-chlorocarbonamide and a salt of a polymericcarboxylic acid.

The invention is illustrated by the following examples, in which partsare by weight.

Example I Arnzen cloth is dipped in a 5% aqueous solution of the sodiumsalt of a 1:1 styrene/maleic anhydride interpolymer, wrung out, thendipped in a 5% aqueous solution of zinc chloride to precipitate the Zincsalt of the polymer into the fabric. ter rinsing and drying at 70 C.,the cloth is impregnated with a solution of 8.5% ofN,N-di(2,4,6-trichlorophenyl)-N,N' di chlorourea and 6.5% ofchloroparafiin in tetrachloroethane at 70 C., the chloroparaiiin servingas a binder for the chlorourea. The impregnated fabric resists thepassage of mustard gas vapor and is found to have lost none of itstensile strength after 48 hours at 70 C. and 100% relative humidity,whereas a control fabric impregnated similarly except for the omissionof the pretreatment loses all tensile strength under the same testconditions.

The preparation of interpolymers of the kind mentioned in the foregoingexample is described in United States Patents 1,976,679 and 2,047,398.

Example II Thirty (30) parts of N,N'-(2,4,6-trichlorophenyl)-N,N'-dichlorourea is dry blended with 3 parts of a 75/25 sodiumpolymethacrylate/polymethylmethacrylate interpolymer and 0.6 part oftechnical sodium dodecyl sulfate. Thirty (30) parts of the above mixtureis stirred with 120 parts of water until a uniform paste is obtained.all of which is impregnated into one square yard of olivehtates Patent3,3432% Patented May E5, 1962 drab muslin. There is obtained a mustardgas-resistant fabric of good appearance which, upon being subjected to atemperature of 115 F. at relative humidity for 56 days, retains 61% ofits original chlorine and 56% of its original tensile strength. Acontrol treatment without the sodium polymethacrylate/polymethylmethacrylate interpolyrner gives a fabric which loses practically alltensile strength under the same conditions.

Example III The above example is repeated except that 10 parts of zincoxide is added to the treating composition. The impregnated fabric uponbeing subjected to the same testing conditions, shows the same tensilestrength retention, but the percent chlorine retained is 76%.

Example IV A /2 x 1 yard swatch of herringbone twill is soaked in asolution of 5.8 parts of sodium cellulose glycolate of medium viscosityin 290 parts of water, wrung to a weight pick-up and dried at 76 C. for15 minutes. The fabric is then dipped at 60-65 in 500 parts of asolution prepared by dissolving 85 parts of N,N-(2,4,6-trichlorophenyl)-N,N-dichlorourea and 64 parts of chloroparaffinin 850parts of tetrachloroethane, wrung on a rubber roll wringer to wet weightand dried 15 minutes at 76 C. Upon subjecting the treated fabric to atemperature of 70 C. and 100% relativehumidity for 48 hours, it is foundto have retained 46% of its initial chlorine content and 35% of itsinitial tensile strength. Under the same conditions, a control fabricsimilarly impregnated with the exception that the pretreatment wasomitted retains only 7% of its original chlorine content and 1% of itsoriginal tensile strength.

In the above examples, the percent chlorine retained refers to theresidual amount of active, or titratable chlorine as measured by theamount of iodine liberated from potassium iodide. A known area of fabricis extracted with a tetrachloroethane-acetic acid mixture (3:2 byvolume), excess potassium iodide solution is added, and the iodineliberated is titrated with standard sodium thiosulfate solution. Thepercent tensile retained is the ratio of the tensile strength of thefabric after aging un der simulated tropical conditions to the tensilestrength of the original fabric before impregnation, measured by thestandard A.S.T.M. Grab tensile test.

The stabilizers suitable for the purpose of this invention are salts ofpolymeric polycarboxylic acids, the term polymeric having here itsaccepted connotation of high molecular weight, i.e. macromolecular,materials (see, for example, Gilmans Organic Chemistry, Second Edition,vol I, pages 10, 702, and 739). The polymeric car boxylic acids containrecurring structural units each containing at least one carboxylic acidgroup. Salts of the polymeric carboxylic acids with any metal aresuitable, but the preferred salts are the alkali and alkaline earthmetal salts, especially the former. Further examples of suitable agentsare potassium polyacrylate, the sodium salt of polyvinyl alcoholglycolic acid ether, the sodium salts of vinyl acetate/maleic anhydrideinterpolymers, etc.

The salt may be applied to the fabric together with the N-chloroamide,e.g. as an aqueous solution in which the N-chloroamide is suspended oremulsified. However, the best results are achieved when the polymericacid salt is used in a pretreatment operation.

The polymeric acid salt is most conveniently applied to the fabric inthe form of an aqueous solution, hence the alkali salts, which areWater-soluble, are preferred. If desired, however, the fabric may befirst treated with a solution of an alkali salt of a polymericcarboxylic acid or of the free acid, then with a water-soluble inorganicacid salt of another metal so as to precipitate the polymeric acid saltof the other metal on the fabric.

The invention has been illustrated With particular reference toN,N-(2,4,6-trichlorophenyl)-N,N-dichlorourea as the anti'vesicant agent.However, any N-chlorocarbonamide is suitable, includingN-dichlorotrichloroacetamide, N-dichlorobenzamide etc. A preferred groupis that of the tertiary N-chloroureas, i.e., compounds having the ureanucleus NCON in which the nitrogens are joined only to chlorine andcarbon free from hydrogen. Examples of this group areN,N-di-(2,6-dimethylphenyl)-N,N'-dichlorourea; 1,3,4-,6-tetrachloro-3a,-6a, dimethylglycoluril; -methyl-5-isobutyl1,3-dichlorohydantoin;N,N'-dichloro-5,5-dimethyl hydantoin, etc.

The chloroamide may be applied to the fabric as a solution in a volatileorganic solvent non-reactive therewith. Suitable solvents include thechlorinated hydrocarbons such as tetrachloroethane, tetrachloroethylene,ethylene dichloride, chloroform, chlorobenzene, or the ethers such asdioxane and glycol dimethyl ether. It may also be applied as an aqueousdispersion, using a suitable dispersing agent such as polyvinyl alcohol,partially hydrolyzed polyvinyl acetates, polyethylene oxides, sultonatedalkylbenzenes, sulfonated naphthalene-formaldehyde condensationproducts, hydrolyzed reaction products of mineral oils with chlorine andsulfur dioxide, or sulfated long chain alcohols.

A binder for the chloroamide is often desirable, though not essential.For this purpose can be used any substantially non-volatile, usuallywater-insoluble material nonreactive toward the chloroamide. The binderis preferably a highly viscous liquid or semi-solid at room temperature.Suitable binders are chlorinated paraifin wax (40-45% chlorine), methylcellulose, polyisobutylene, mineral oil etc.

The fabric-treating compositions may comprise, in addition to thepolymeric carboxylic acid salt, other agents capable of retarding fabricdeterioration and chloroamide decomposition. Among these, zinc oxide andcalcium carbonate are particularly useful. The fabric-treatingcompositions may also contain other materials such as pigments, dyes,water-repellents, etc.

While the polymeric carboxylic acid salts are particularly useful forthe treatment of cellulosic textile fibers and fabrics to prevent orretard their loss of strength and to minimize the loss of activechlorine from the N-chloroamide in contact with the fabric, they mayalso be applied with beneficial results to any other cellulosic fabricor web, such as paper, or to other cellulosic materials such asregenerated cellulose fibers or films, cotton, wooden surfaces and thelike. From such treated materials, after subsequent treatment with anN-chloroamide may be made such articles as antiseptic bandages, wallpaper, and coverings for any surface where slow, controlled liberationof chlorine is desired.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that I do not limit myself to the specific embodimentsthereof except as defined in the appended claims.

I claim:

1. Cellulosic material which is resistant to penetration by mustard gasand which contains an N-chlorocarbonamide and an alkali metal salt of apolymeric carboxylic acid selected from the group consisting ofstyrene/rnaleic anhydride interpolymer, polymethacrylicacid/polymethylmethacrylate interpolymer, cellulose glycolic acid,polyac'rylic acid, polyvinyl alcohol glycolic acid ether, and vinylacetate/maleic anhydride interpolymer.

2. The cellulosic material set forth in claim 1 in which said salt isthe sodium salt of a 1:1 styrene/maleic anhydride interpolymer.

3. The cellulosic material set forth in claim 1 in which said salt issodium polymethacrylate/polymethylmethacrylate interpolymer.

4. The cellulosic material set forth in claim 1 in which said salt issodium cellulose glycolate.

5. The cellulosic material set forth in claim 1 in which saidN-chlorocarbonamide is N,N-di(2,4,6-trichlorophenyl -N,N-di-chlorourea.

6. Clothing which is resistant to penetration by mustard gas and whichcontains an N-chlorocarbonamide and an alkali metal salt of a polymericcarboxylic acid selected from the group consisting of styrene/maleicanhydride interpolymer, polymethacrylic acid/polymetbylmethacrylateinterpolymer, cellulose glycolic acid, polyacrylic acid, polyvinylalcohol glycolic acid ether, and vinyl acetate/- maleic anhydrideinterpolymer.

7. A process for obtaining cellulosic material resistant to penetrationby mustard gas, said process comprising treating the cellulosic materialwith an N-chlorocarbonamide and an alkali metal salt of a polymericcarboxylic acid selected from the group consisting of styrene/maleicanhydride interpolymer, polymethacrylic acid/polymethylmethacrylateinterpolymer, cellulose glycolic acid, polyacrylic acid, polyvinylalcohol glycolic acid ether, and vinyl acetate/maleic anhydrideinterpolymer.

8. A cellulosic vesicant-resistant, permeable fabric which contains atertiary N-chlorourea and a metal salt of an interpolymer of styrene andmaleic anhydride.

References Cited in the file of this patent UNITED STATES PATENTS2,173,781 Gibello Sept. 19, 1939 FOREIGN PATENTS 486,162 Great BritainMay 31, 1938 OTHER REFERENCES Technical Abstracts, vol. III of 1944,page 737,

1. CELLULOSIC MATERIAL WHICH IS RESISTANT TO PENETRATION BY MUSTARD GASAND WHICH CONTAINS AN N-CHLOROCARBONAMIDE AND AN ALKALI METAL SALT OF APOLYMERIC CARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OFSTYRENE/MALEIC ANHYDRIDE INTERPOLYMER, POLYMETHACRYLICACID/POLYMETHYLETHACRYLATE INTERPOLYMER, CELLULOSE GLYCOLIC ACID,POLYACRYLIC ACID, POLYVINYL ALCOHOL GLYCOLIC ACID ETHER, AND VINYLACETATE/MALEIC ANHYDRIDE INTERPOLYMER.